Reducing near-surface voids in metal (Ti-6Al-4V) powder bed fusion additive manufacturing: the effect of inter-hatch travel time

Abstract

Powder bed fusion additive manufacturing (L-PBF) is being rapidly adopted by industry for the production of novel and complex geometries. However, production of L-PBF parts with near-surface voids remains a primary concern. Such voids impede the use of additive manufacturing for thin geometries and may significantly reduce fatigue life. Here, we develop a statistical model which relates the probability of near-surface void formation to toolpath parameters used in part production. Using registered computed tomography (CT) data as ground truth to measure void location and morphology together with actual build plan data (e.g. vector trajectories, powers, speeds), we identify the time between nonconsecutive, adjacent hatch strikes to be a statistically significant (p = 8.54 × 10-20) indicator of the likelihood that a given point becomes a void. Furthermore, we show that altering hatching strategy to include fewer short hatches (i.e. a longer time between nonconsecutive, adjacent hatch strikes) can produce a similar geometry with significantly fewer near-surface voids.